"I simply didn't have enough time [before London] to prepare the way I wanted to and I had to compromise."

He continued: "Now I can do exactly the training that I need to do with time on my side and I can get a preparation that will enable me to swim really well."

Australian head coach Leigh Nugent admits it would be "a big ask" for Thorpe to return to the form in which he won three Olympic titles in his home Games in Sydney in 2000, and two more in Athens four years later.

"Ian is such an enigmatic character and a brilliant athlete, but if you really haven't got that gut burning desire to do it well then maybe you have to look at other things," Nugent told BBC Sport.

"His heart is in swimming but whether it's in the type of work that he needs to do to get where he'd like to be remains to be seen."

Thorpe, who dominated the 400m freestyle event between his World Championship debut in 1999 and the 2004 Athens Olympics, axed the event for his comeback bid.

He admitted taking a "ego bashing" after focusing on the 100m and 200m events as a sprinter and Nugent believes the 10-time Commonwealth champion needs to return to his previous guise as a middle-distance specialist.

"His physiology suits the 200-400m area and to try and break into the sprint area is pretty tough for him," explained Nugent.

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Thorpe's secret Olympic training base

"He needs to settle down and really apply himself to the sort of types of training that he would need to do for the 200m in particular."

At present Thorpe, who would be 33 by the time of the Rio Olympics in 2016, is only thinking about racing over the next two years, which could potentially include the 2014 Commonwealth Games in Glasgow.

And he admits he dreams of a return to the top of his sport once more.

"It would be nice to allow myself to come full circle in my swimming career," added Thorpe.

"I've gone from a child who loved what they did, to really having that taken away from me and then being told I'm too old and too tired [when attempting a comeback].

"Having success again would be what that younger athlete I once was would tell me to do."

The Australian trials (external) run from 26 April to 3 May, ahead of the World Championships which take place in Barcelona between 19 July and 4 August.